Brain Scans Show How Teens Are More 'Me-First' Than Adults

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So he failed to hold the door for you — he's a teen, what do you
expect? Scientists and the average adult have known young
adolescents to be selfish. With brain-scanning technology,
researchers are now figuring out how most of these "delinquents"
transform into respectable adults.

A study involving a trust game revealed that 12- to 14-year-olds
use a part of their brain linked to self-oriented thought and
what's-in-it-for-me thinking when they make decisions about
whether to share with others. Older teens and young adults use
this "me" part of their brain when acting selfishly; for
pro-social decisions, their brains charge up an area linked to
taking others' perspectives into consideration, the researchers
found.

The findings, detailed in the January 2011 issue of the journal
Psychological Science, suggest these brain changes underlie the
behavioral transformations as teenagers grow up. [ 7
Ways the Mind and Body Change With Age ]

Trust game

Sixty-two paid volunteers (about evenly split between male and
female) played the trust game inside a functional magnetic
resonance imaging machine (fMRI), which measures blood
flow to different areas of the brain as a way
to pinpoint
brain activity .

In the trust game, one of the players (Player 1) can either share
a certain amount of money equally with another player or giving
the entire sum to that player. If Player 1 divides the money
equally, the game ends. But if Player 1 does give it all to the
other player, the amount of money increases and at this point
Player 2 has the choice to share that amount with Player 1 or
keep most of the money (called defecting).

The researchers, including Wouter van den Bos of Leiden
University in the Netherlands, put study participants in the role
of Player 2, telling them that Player 1 had already made their
decisions in a prior round of the game. Participants were also
told they would be rewarded financially for their trust-game
decisions.

Some of the trials were considered low-risk, in which
participants were told Player 1 had given them only a small sum
(and as such did not stand to lose much if they did not
reciprocate). Higher-risk trials were the ones in which Player 1
provided a large sum of money.

All about me

To analyze the results, the researchers divided participants into
three age groups, based on teens' developmental stages: pubertal
early adolescents (ages 12-14), postpubertal mid-adolescents
(15-17), and young adults (18- 22).

On average, participants reciprocated in about half of the
trials, but the results varied by age group.

The mid-adolescents and young adults showed more reciprocity
during the high-risk trials than during the low-risk ones. To the
researchers, the difference hinted that the older age groups "got
it" — that they were thinking along the lines of, "Oh, Player 1
is really putting himself out for me and trusted that I'd
reciprocate."

The youngest adolescent group showed no difference between the
low- and high-risk trials. "They were always just thinking more
about their own outcomes," Van den Bos told LiveScience.

The brain results paralleled the behavior findings. When acting
selfishly (defecting), all age groups showed similar brain
activity in the medial
prefrontal cortex, a region involved in self-oriented
thought. However, brain activity in the "self" region did not
show up during reciprocation for mid-adolescents and young
adults, while it did for younger teens.

"An interesting avenue for future researchers is to test the
hypothesis that even when reciprocating, young adolescents are
engaged in self-referential thoughts," the researchers wrote.

In addition, activity in the brain's temporo-parietal junction
(TPJ) increased with age. This area, where the temporal lobe
(just above your ear) and parietal lobe (toward the back of your
head) meet, is thought to be important for shifting attention
between one's own and other perspectives and for inferring the
intentions of others, the researchers wrote.

The change in activity with age suggests a shift in attention
from self to others during adolescence, the researchers said.

The research was supported by a Vidi grant from the Netherlands
Organization for Scientific Research.